EP 01 - Les résistances

Introduction

In this tutorial, we will explore the fundamentals of resistors in electronics, based on the first episode from Electronique Pratique. This guide will help beginners understand the types of resistors, how to read their values, and the principles behind their use in circuits.

Step 1: Understanding Resistors

• Resistors are components used to limit the flow of electric current in a circuit.
• They are essential for controlling voltage and protecting sensitive components.
• Resistors come in various forms, including through-hole and surface mount (CMS) types.

Step 2: Learning the Color Code

• Resistors use a color coding system to indicate their resistance values.

• Each color corresponds to a number, with the first two or three bands representing significant digits and the last band representing the multiplier.

• To decode the color, refer to the following chart:

  | Color | Digit | |-----------|-------| | Black | 0 | | Brown | 1 | | Red | 2 | | Orange | 3 | | Yellow | 4 | | Green | 5 | | Blue | 6 | | Violet | 7 | | Gray | 8 | | White | 9 |

• Use the following resource for more on color coding: Code de couleur des résistances.

Step 3: Applying Ohm's Law

• Ohm's Law is fundamental in understanding resistors. It states:

  [ V = I \times R ]

  Where:

  • V = Voltage (Volts)
  • I = Current (Amperes)
  • R = Resistance (Ohms)

• This formula allows you to calculate the voltage drop across a resistor or the current flowing through it.

Step 4: Identifying Parasitic Resistances

• Parasitic resistances are unintended resistances in a circuit that can affect performance.
• Be aware of these when designing circuits, as they can alter expected outcomes.

Step 5: Calculating Power Dissipation

• Resistors dissipate power in the form of heat, calculated using the formula:

  [ P = I^2 \times R ]

  Where:

  • P = Power (Watts)

• Ensure that the resistor can handle the power without overheating. Use resistors rated for higher wattage if necessary.

Step 6: Connecting Resistors in Series

• When resistors are connected in series, the total resistance increases:

  [ R_{total} = R_1 + R_2 + R_3 + \ldots ]

• The same current flows through each resistor, but the voltage drop across each will vary.

Step 7: Connecting Resistors in Parallel

• In parallel, the total resistance decreases:

  [ \frac{1}{R_{total}} = \frac{1}{R_1} + \frac{1}{R_2} + \ldots ]

• The voltage across each resistor is the same, while the current may differ based on the resistance values.

Conclusion

In this tutorial, we've covered the basics of resistors, including their purpose, how to read their values using the color code, the application of Ohm's Law, and how to connect them in series and parallel configurations.

For further study, consider exploring the resources provided for a deeper understanding of resistor markings and behavior. This foundational knowledge will be essential as you progress in your electronics journey.